1. Field of the Invention
The present invention relates to an image forming apparatus, such as a color photocopier and a color printer, of the electrophotographic type or the electrostatic recording type.
2. Related Background Art
FIG. 5 is a schematic sectional view of an image forming apparatus for better understanding of the present invention.
As shown in FIG. 5, an image scanning unit 101 emits light A such as laser light, so that a photosensitive drum of a process cartridge 102 is irradiated with the light A. The light A, which irradiates the photosensitive drum, forms a latent image on the photosensitive drum, thereby allowing a toner image formed by specified development means to be transferred onto an endless intermediate transferring unit one after another.
The process cartridge unit 102 incorporates means for charging the photosensitive drum, or development means for forming the toner image. The toner-supplying container 104 is disposed for supplying the process cartridge 102 with toner.
A toner-supplying container 104 of larger volume requires less frequent replacement of the container; however, it ends up requiring a larger image forming apparatus. For this reason, the toner-supplying container 104 is disposed between two adjacent image scanning units 101 so that space in the apparatus can be utilized effectively.
The toner-supplying container 104 disposed between two adjacent image scanning units 101 is detachably mounted in the apparatus, since the container needs to be replaced with a new one when toner in the cartridge is used up. The toner-supplying container 104 is inserted into the image forming apparatus along the mount plate 103 for mounting the image scanning unit 101, and is mounted in the apparatus by supporting means (not shown). As described above, the toner-supplying container 104 is mounted in the apparatus by using a guide plate, for example, the mount plate 103, as a guide member, for mounting the image scanning unit 101.
In an apparatus for forming a color image by superimposing one toner on another of a plurality of colors, the positional relationship among the image forming stations for different colors is critical. It is, however, extremely difficult to have a positional relationship within a desired limit among image scanning units, if a plurality of image scanning units 101 are mounted on separate mount plates 103 as in the above-described image forming apparatus. The failure of having the positional relationship within a desired limit may cause a color aberration.
Therefore, it is envisioned that the positioning accuracy of the plurality of image scanning units is improved by mounting them on a single supporting member. However, a color image forming apparatus having a plurality of image forming stations in a tandem manner generally includes three to four image scanning units, thereby giving rise to such a problem that the supporting member becomes large accordingly, and thus it is difficult to keep enough stiffness of the supporting member.
In view of the above-described problem, it is an object of the present invention to provide an image forming apparatus with high mounting accuracy of image scanning units.
It is another object of the present invention to provide an image forming apparatus with high frame stiffness.
It is a further object of the present invention to provide an image forming apparatus having: a plurality of image forming stations for forming an image, each of the image forming stations comprising an image scanning unit and toner cartridges, the toner cartridges being detachably mountable on a main assembly of the apparatus; a supporting member for supporting the image scanning units; and a plurality of guide members for guiding the toner cartridges, wherein the plurality of guide members are fixed to the supporting members.
Further objects of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.